Today’s [Triviatime](https://triviatime.app/) had a Q which asked what % of the earth’s air is made of Oxygen. The answer was 21% but this only left me with more questions!
How??? What else is there and what are the implications of those elements/things being literally everywhere in the air. Fellow laymen eggheads, please add to this list of thoughts you have about this which need to be addressed:
– How does our breathing filter the other stuff out?
– What actually is air if it’s made up of so many different things, I thought air basically = oxygen?
– How steady is this 21% level? Can this change overtime, is that dangerous, and if so how?
– Etc
In: 0
Most of the air you breathe is nitrogen- about 80%. Nitrogen is inert, and your body doesn’t care about its molecular form. The molecular form is so stable that the only way for you to get the nitrogen your body needs is to eat it, and the way it got into your food is that many plants have symbiotic bacteria in their roots that convert molecular nitrogen into bioavailable nitrogen. When you take in a lung full of air, molecular oxygen is taken up by your red blood cells while the molecular nitrogen is more happy to remain as a gas.
The amount of oxygen in the atmosphere does change over time, but usually over geologic time periods, and it’s always much less than nitrogen. Hundreds of millions of years ago the atmospheric oxygen concentration was closer to 30%, and one of the ways we know this is from fossils of the enormous insects that lived back then- dragonflies with a 60 cm wingspan, or millipedes 2 meters long.
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